Intelligent Transportation Systems (ITS) are systems which aim to improve road safety by broadcasting real-time information pertaining to the road conditions. For example in such systems, cars or similar vehicles may broadcast information such as position, speed, road conditions, events and/or accidents. This information may be shared between vehicles using so-called Vehicle to Vehicle (V2V) communication and vehicles and other units such as road side entities or traffic control units using Vehicle to Infrastructure (V2I) communication. These communication systems may use IEEE 802.11p dedicated short range communication (DSRC) technology.
One application of ITS may provide vehicle platooning. Such vehicle platooning may automatically group a number of vehicles to travel together in an actively coordinated way, for example forming a train of vehicles. Vehicle platooning may be desired in order to improve road usage capacity and mitigate traffic, improve fuel efficiency, safety and driver comfort.
In order to co-ordinate such platooning, platooning control algorithms may be provided in each vehicle in the platoon to control that vehicle to hold itself in the platoon. These control algorithms may control vehicle parameters such as speed and acceleration. Such control algorithms may control the vehicle in response to receiving information about the platoon behavior from sensors on the vehicle or from other members of the platoon and/or other entities. For example, the algorithm may operate based on information received from radar sensors of the vehicle and/or V2V communication.
An aim of such a control algorithm may be to hold the vehicle in the platoon such that there is a relatively small distance between the member vehicles of the platoon. A smaller vehicle to vehicle distance or gap may result in less airflow resistance and thus less fuel consumption.
The Adaptive Cruise Control (ACC) system in a vehicle may use radar and/or laser sensors to follow a vehicle directly preceding it. An ACC may not see any of the vehicles preceding its direct predecessor in the platoon and this may lead to a one-by-one propagation of any actions of a vehicle leading the platoon. Such one-by-one propagation may be adjusted for by providing a larger gap or travelling distance between platoon members.
In ITS, Common Awareness Messages (CAMs) may be broadcast at a 10 Hz rate by which each vehicle may broadcast information about itself using a control channel. Such information may comprise position, speed, acceleration and actions of the vehicle. Using CAM, a vehicle may use one message to broadcast such information to multiple vehicles simultaneously.
In cooperative adaptive cruise control (CACC), a vehicle may use information not only from its predecessor but also from other members of the platoon. While in some cases, a CACC system may limit propagation of disturbances throughout the vehicle chain in comparison to ACC due to the additional information, the increase in messages used to convey such information may be subject to network delay or problems associated with imperfect messaging mediums.
Embodiments of the present application aim to provide a method of vehicle platooning control while taking in account these real-world constraints.